The São Francisco River Basin (SFB) in NES is the third largest watershed in Brazil, occupying 8% of the country (~640.000 km²) ( Figure 1 ). It crosses six Brazilian States and is divided into four physiographic regions: Low (5% of the watershed), Sub-Medium (17% of the watershed), Medium (39% of the watershed), and High São Francisco (~40% of the watershed) (MMA, 2006).

The SFB still holds 57% of its native vegetation cover (MMA, 2006; Mapbiomas Project 2022b). The remaining area is intensively anthropized mainly by pasture (23% of the basin), agriculture (5%), or both (11%) (Mapbiomas Project, 2022b; Figure 1 ). The watershed covers a myriad of climates and vegetation types within three out of the five naturally occurring vegetation types, called “biomes” in Brazil: Cerrado savannas, Caatinga seasonally dry forests, and Atlantic Forest rainforest ( Figure 1 ).

The SFB is vital for ES provision in Brazil, with over 70% of its water used for grain and fruit irrigation, primarily for exports (MMA, 2017). Its waters are also responsible for 12% of the national hydropower production (Marengo et al., 2019; da Silva et al., 2021). It accounts for 12% of national hydropower production (Marengo et al., 2019; da Silva et al., 2021), significantly impacting Brazil’s GDP. Facing the greatest socio-economic impacts from natural climatic variability (Brasil, 2006; Marengo et al., 2012), the São Francisco River, central to the SFB, sustains traditional communities such as Indigenous Peoples, quilombolas(Afro-Brazilian descendants of escaped enslaved people who formed autonomous communities in settlements known as quilombos), family farmers, artisanal fishermen, extractivists and gipsy communities (Niemeyer and Vale, 2022; MMA, 2016). The Northeast region alone holds 17% of Brazil’s Indigenous Peoples and more than half of the quilombolas communities (Damasco and Antunes, 2020). These are the most vulnerable population due to their low political representativeness and high cultural value, often unique and irreplaceable. Although there have been little empirical studies that explore the cultural, emotional and spiritual attachments to land and landscapes through interviews or participatory methods, it is widely recognized that a sense of place (sensu Casey, 2001) - enhances communities’ resilience and adaptation capacity to global changes (Selfa et al., 2021).

For centuries, traditional communities in the SFB have shaped their livelihoods and history attached to their lands through adaptation and resistance, learning how to coexist with the Semiarid and keeping up with the São Francisco River’s natural cycles (Moulin et al., 2021; Niemeyer and Vale, 2022). The SF River has many names (Velho Chico, Parapitinga and Opará) and serves the communities who depend on it not only for food and water, but also as a cultural and spiritual reference (MMA, 2017). Locals report that the piracema (the fish migration period), as well as folkloric beings linked to rivers, such as Iara and Caboclo d’Água, are no longer seen due to the impacts of global changes and dam construction (Moulin et al., 2021). Future climate change impacts are expected to worsen, leading to the loss of unique and irreplaceable cultural ES tied to the land and the SF River. It will also exacerbate agricultural productivity and water supply challenges, further increasing food and water insecurity, particularly for the most vulnerable and impoverished populations (Marengo et al., 2018).

We used the IPCC (2014) framework ( Figure 2 ) to assess climate risk in SFB municipalities, focusing on the three main components: hazard, exposure, and vulnerability. Climate risk results from the interaction between hazards, exposure, and vulnerability of human and natural systems (IPCC, 2018; Foden et al., 2019; Pörtner et al., 2022). Hazards are climate-induced physical events, trends, or their physical impacts that may adversely affect socio-ecological systems (IPCC, 2018; Foden et al., 2019). Exposure comprehends the presence of people, human and cultural assets, species, or ecosystems in places that could be adversely affected by climate change (IPCC, 2018; Foden et al., 2019). Finally, vulnerability is the propensity or predisposition of a system to be adversely affected by the effects of climate change (IPCC, 2018; Foden et al., 2019). We mapped various variables associated with each component ( Figure 2 ).

We analyzed risk at the municipal level, as local adaptation strategies are best developed at this scale, with municipalities having the autonomy to enact regulations and collaborate with neighboring areas (Kasecker et al., 2018; da Silva et al., 2017). Municipalities are places where on-ground actions occur, such as urban development, environmental protection, and provision of water supply and sanitation (Alves et al., 2020), and where national plans, such as the National Adaptation Plan, may succeed or fail (da Silva et al., 2017). Our analysis included all municipalities that had their centroid inside the SFB limits, using the IBGE database, totaling 452 municipalities.

We computed mean values for each risk component variable per municipality and categorized them into four groups based on quantiles, where the lowest values fell on the first quartile, and the highest values fell on the fourth quartile. High-risk municipalities were those with high hazards, vulnerability, and exposure concurrently ( Figure 3 ). We selected municipalities falling into the quartile with higher land use change or climate anomaly values (high hazard); lower ES values, or higher sense of place values, and lower IDHM values or higher IVS values (high vulnerability); and higher population density (high exposure). All analyses were spatially explicit, with maps of ~1km x 1km spatial resolution and SAD69 projection.

By 2050, the SFB may lose 331,000 km² of native vegetation, a 26% reduction from 2013, mainly in the Medium and Sub-Medium São Francisco regions dominated by Cerrado and Caatinga vegetation ( Figures 4A, B ). The Medium São Francisco exhibits higher potential climate anomalies, particularly under pessimistic scenarios, as expected ( Figures 4B, C ). Municipalities generally experience medium to high potential climate anomaly, showing consistent spatial trends across scenarios ( Figures 4E, F ). Therefore, we opted to utilize climate anomaly projections from the pessimistic scenario for subsequent analyses.

Worrisomely, climate and land use changes spatially coincide, with the Medium São Francisco predicted to endure the most pronounced changes ( Figures 4 , 5 ). In contrast, municipalities in the High São Francisco region primarily experience minimal climate and land use alterations. Among the 455 municipalities analyzed, 9% were in the highest hazard category, most within the Medium São Francisco, covered by Cerrado (red municipalities in Figure 5 ). Meanwhile, 10% fell into the lowest hazard category, mostly in the High São Francisco and covered by Atlantic Forest (blue municipalities in Figure 5 ). See Supplementary Table SM4 and the online dashboard ² for result details.

There are 113 municipalities under high exposure, i.e. have high population density ( Figure 6 ), 45% of which are in the High São Francisco region, and 42% in the Low São Francisco region, mostly within the Atlantic Forest (48%). Conversely, of the 114 municipalities that are under very low exposure, 66% are in the High São Francisco region, and 35% are in the Medium São Francisco region, mostly within the Cerrado (85%).

Ecosystem services (ES) exhibited idiosyncratic spatial patterns ( Figure 7A ). Carbon stock and water yield were lower in the Sub-Medium and Low São Francisco regions, increasing southwards towards the High São Francisco. Water yield was also higher in the Medium and High São Francisco areas. Water quality remained consistently high across the basin, although slightly elevated in the Sub-Medium São Francisco. Erosion control had moderate to low values basin-wide. The sense of place was relatively higher in the Sub-Medium São Francisco and lower in the Medium and High São Francisco regions.

Most municipalities (78%) had high vulnerability to at least one ES ( Figure 7B ). None were highly vulnerable to all ES simultaneously, though one (Catuti, Minas Gerais state) showed high vulnerability to four ES, excluding the sense of place, presenting medium cultural value. Additional municipality details are available in Supplementary Table SM4 . Primarily, highly vulnerable municipalities were in the Sub-Medium and Low São Francisco regions, mainly within Caatinga vegetation, occasionally Cerrado. However, for water quality, the most vulnerable municipalities were in the Medium and High São Francisco regions.

Socioeconomic indices revealed a consistent trend, with the highest vulnerability (low IDHM and high IVS) clustered in the Sub-Medium and Low São Francisco, contrasting with low vulnerability in most High São Francisco municipalities ( Figure 8 ). Lower IDHM and higher IVS values indicate higher socioeconomic vulnerability.

Most municipalities (94%) with high socioeconomic vulnerability in the SFB are in the Caatinga biome, in the Northeast region ( Figures 8C, D ). About 83% of municipalities intersected very low IDHM and high IVS, with all but one located in the Sub-Medium or Low São Francisco. Additional details are provided in Supplementary Table SM4 and interactive spatial visualization is provided in the online dashboard.

Municipalities under higher risk are in the intersection between hazards, exposure, and vulnerability ( Figure 9 ). Fifteen municipalities in the SFB were identified as high-risk, combining all three components (red in Figure 9 ), with some in the Sub-Medium and most in the Low São Francisco. Additionally, 97 municipalities (21%) intersect two risk components: 52 with high hazard and vulnerability (blue in Figure 9 ), 29 with high exposure and hazard (light green in Figure 9 ), and 16 with high exposure and vulnerability (lilac in Figure 9 ). Further details on municipalities and their risk components are available in Supplementary Table SM4 and interactive spatial visualization is provided in the online dashboard.

Our findings indicate higher hazards in municipalities of the Northwest (Medium São Francisco) (Vieira et al., 2020). Deforestation is projected to primarily impact the Cerrado and Caatinga regions in the North and Northeast of the SFB. Notably, in 2021, Cerrado and Caatinga ranked as the second and third most deforested biomes in Brazil (Mapbiomas Project, 2022a). In the Caatinga, chronic deforestation accelerates land degradation, increasing desertification risk (Vieira et al., 2020). High aridity and land degradation could also increase fire susceptibility, under a positive feedback that further exacerbates desertification (Castellanos et al., 2022; Vieira et al., 2020; Viegas et al., 2022). Indeed, fire occurrences related to agricultural expansion in the Caatinga increased by 167% between 2020 and 2021 ³ . Additionally, desertification is associated with carbon emissions from soil and vegetation, underscoring the global significance of preserving Brazilian dry forests as potential carbon sinks (Fernandes et al., 2020, 2021).

Our study identified a water quality gradient, declining from the High to the Low São Francisco, consistent with prior research (Bettencourt et al., 2016; MMA, 2017). However, this does not imply that the Northeast is devoid of water quality issues, as approximately 55% of the region’s water is unfit for human consumption, and 77% of the Low São Francisco has water unsuitable for irrigation (MMA, 2017). Anthropic activities have contributed to water quality deterioration (Bettencourt et al., 2016; MMA, 2017). Water scarcity is projected to be exacerbated by climate change-induced aridity and rising irrigation demands, which currently represents 77% of water withdrawals (Lucas et al., 2021; Paredes-Trejo et al., 2021; da Silva et al., 2021; Vieira et al., 2020). Freshwater ecosystems and biodiversity are also impacted, as is shown by the decreased productivity of traditional artisanal fishing (MMA, 2017).

The São Francisco River, Brazil’s national integration river, has lost 50% of its natural water surface in the last three decades, and hydroelectricity generation is declining (Mapbiomas Project, 2022b; da Silva et al., 2021). Anticipated rainfall reductions by 2100, possibly as early as 2050, will impact water availability and hydropower generation, and hydroelectricity production in the SFB could completely cease during drought years by 2030 (de Jong et al., 2018). These projections are expected to exacerbate socio-environmental vulnerabilities and conflicts over water, leading to population migration to other regions (Marengo et al., 2012; Forcella et al., 2015).

Our findings suggest low erosion control throughout the São Francisco River. Scarce yet intense rainfall increases surface runoff and sediment transport, negatively impacting river sedimentation, hydropower generation, and water quality (Bettencourt et al., 2016). Recovery of riparian vegetation could be an important EbA strategy in municipalities most affected by river sedimentation and water degradation (Holanda et al., 2005, 2009). Strengthening and enforcing the Native Vegetation Protection Law could support such efforts (Niemeyer et al., 2020). Restoration efforts could focus on species providing food and medicine to boost income generation and engage landholders (Holanda et al., 2005).

It is important to note that the water yield, water quality, and erosion control results derived from widely used, although simplified, models (Sharp et al., 2018), that potentially deviate from reality due to limited local-scale data for model parametrization. Still, we used concise, reliable information from studies within or near the SFB region. Moreover, water demand should be included in future analysis, which could impact high-risk area identification. Thus, the information provided here serves to evaluate the relative potential for ES provision within the region, being an initial step in the decision-making process.

The Northeast region holds the highest sense of place value within the SFB, representing individuals’ attachment and identity to their surroundings (Adger et al., 2013). Indigenous and quilombola territories in Brazil effectively mitigate deforestation, foster regrowth, and are pivotal for biodiversity and ES conservation (Lima et al., 2020; Resende et al., 2021; Alves-Pinto et al., 2022), playing a key role in guaranteeing human wellbeing and supporting climate change adaptation (Scarano, 2017; Pires et al., 2018). Additionally, Semiarid communities have developed cultural practices and social technologies to adapt to climate-related risks. Incorporating local knowledge into policy frameworks can enhance the effectiveness and scalability of adaptation initiatives, as demonstrated by the success of the 1 Million Cisterns Program (P1MC) (Niemeyer and Vale, 2022). The P1MC is a large-scale initiative to provide access to safe drinking water through rainwater harvesting in Brazil’s semi-arid region.

Global impacts on land and ecosystems lead not only to species loss, but also to the disruption of social processes and the loss of ecosystem services (Moulin et al., 2021). Climate change jeopardizes cultural values and expressions, which influence societal responses and adaptations to climate risks (Adger et al., 2013). Cultural ES is often unique and irreplaceable, yet still overlooked in vulnerability assessments (Pires et al., 2018). Indigenous Peoples and local communities are typically the first and most drastically affected by climate change, often displaced from their valued places (Thomas et al., 2019). Territory, human displacement, and indigenous and local knowledge are non-economic losses driven by climate change (UNFCCC, 2024). While the cultural dimension in our analysis remains superficial, our approach offers a valuable starting point to represent people-place relationships, an aspect often overlooked in assessments of ecosystem services and EbA in Brazil (Pires et al., 2021). This is particularly relevant given the historical resistance and claims for ancestral land by Indigenous Peoples and quilombola communities. Still, we strongly encourage that further studies are conducted in direct contact with Indigenous Peoples and local communities. Directly engaging local communities in knowledge co-production fosters inclusivity and should integrate decision-making and EbA policy development (Bourne et al., 2016; Niemeyer and Vale, 2022).

We identified fifteen high-risk municipalities in SFB ( Supplementary Table SM4 ). These areas show relatively low vulnerability to water availability, possibly due to higher relative precipitation. The vast majority are under high hazards related to climate anomaly. Inhabitants of high-risk municipalities have a significant social vulnerability, especially considering the high number of indigenous and quilombolas sites. These communities are particularly vulnerable and should be a focal point for EbA policies. These municipalities have either very low or high susceptibility to land use changes, likely due to extensive pastureland conversion already in place. The Low São Francisco region has the lowest native vegetation percentage under protection (4%) within the basin (Mapbiomas Project, 2022b). Thus, expanding protected areas could be a key EbA strategy to mitigate further deforestation. Policymakers should analyze each risk component of high-risk municipalities and integrate local data to develop and implement effective EbA strategies.

Analyzing risk components helps identify high-risk areas for EbA strategies, improving adaptation capacity. However, local EbA measures contribute, but are not enough in reducing climatic hazards in the short term, requiring large-scale mitigation actions that reduce greenhouse gas emissions or increase their sequestration. Similarly, reducing exposure typically involves resettlement, which is desirable only in disaster-prone situations. Hence, widespread local EbA actions in the SFB would be effective in reducing vulnerability and climate change impact (Garcia et al., 2019) and should be complemented by technological solutions at the regional or watershed scale.

EbA includes ecosystem conservation, restoration, and management (Scarano, 2017). Maintaining natural features increases ecosystems and species’ resilience to climate change, which is crucial for ecosystem service provision, thereby bolstering climate change adaptation and socio-ecological systems’ health (Bourne et al., 2016). Conservation, restoration, and sustainable management are crucial in areas prone to land use changes to bolster climate resilience (Bourne et al., 2016). However, the SFB is inadequately protected: only 7% of its native vegetation lies within protected areas, and just 1% falls within the strictly protected category (Jenkins et al., 2015; CNUC/MMA, 2022). This increases the risk of losing unique species and ecosystem functions. Land use and climate changes exacerbate extinction risks for SFB’s endemic species and the ecosystem services they provide (Manhães et al., 2016; Velazco et al., 2019). This emphasizes the need to expand this protected areas network, including indigenous and quilombolas’ territories, to safeguard species and ES that are essential for local welfare (Velazco et al., 2019; Colli et al., 2020; Resende et al., 2021; Niemeyer and Vale, 2022; Vale et al., 2023).

Payments for environmental services (PES), sustainable forest management incentives, and indigenous rights support may integrate biodiversity and ES conservation with socioeconomic development (Fernandes et al., 2021; Niemeyer and Vale, 2022). Providing technical assistance for sustainable agricultural practices like agroforestry and implementing deforestation-curbing policies could enhance native vegetation regeneration and carbon sequestration in Brazil’s Semiarid region (Fernandes et al., 2021; Niemeyer and Vale, 2022). Designing protected areas that balance biodiversity conservation and ES provision, resilient to climate change, is crucial (Manhães et al., 2016; Velazco et al., 2019).

Hydropower from the São Francisco River is an important energy source for Northeast Brazil (Milhorance et al., 2019) but is already suffering reductions due to drought. which is expected to increase along with climate change. Climate change impacts and increased demand may reduce water availability by up to 50% by 2050 at the Sobradinho hydroelectric plant within the SFB (de Jong et al., 2018; da Silva et al., 2021). Other than investments in irrigation regulations, investing in renewable resources like wind and solar energy are technical solutions that offer cheaper, more sustainable alternatives that are less vulnerable to climate change (de Jong et al., 2018). In 2025, the Northeast is responsible for almost 90% of Brazil’s wind energy production (https://l1nq.com/lHP56), and solar and wind energy production in the region are expected to increase (da Silva et al., 2021; de Jong et al., 2019). However, regulatory frameworks for wind and solar power in the region need improvement due to negative social and ecological impacts resulting from institutional weaknesses, fraudulent licensing, and procedural injustices, which have marginalized local communities from decision-making (Gorayeb et al., 2018). Impacts include wind farms near ecologically significant areas and displacement of Indigenous Peoples and traditional communities lacking formal land titles (Gorayeb et al., 2018; Niemeyer and Vale, 2022).

Given the São Francisco River’s significance and vulnerability to climate change, urgent implementation of a sustainable restoration program is imperative. Proposed in 2001 by the federal government, the Revitalization program aims to enhance socio-environmental conditions, ensure water access, promote sustainable economic activities, and implement preventative measures and improve sanitation (IPEA, 2019; Alves da Silva Rosa et al., 2021). Despite slow progress, it stands as a vital EbA and is key to achieving regional water security (Alves da Silva Rosa et al., 2021; Niemeyer and Vale, 2022).It offers soil conservation benefits and opportunities for soil remediation and native vegetation restoration in low sediment retention areas. Incentives for a more sustainable development are paramount, and the Revitalization program of the SFB must be the center of sustainable investments both in high-risk areas and the SFB entirely.

There are still several obstacles to the effective implementation of EbA. Some of the most prominent challenges in the region include a strong policy focus on infrastructure and engineering solutions rather than on nature-based approaches; conflicts due to land concentration and the political influence of agribusiness; existing policies that fail to effectively reverse social vulnerabilities or enhance climate resilience, further undermining efforts to adapt to changing conditions; biodiversity conservation is still limited in the region, as well as restoration and the Revitalization program; and finally, Brazil’s constant changes in the political environment are a significant challenge to environmental sustainability, being unable to maintain some EbA-key policies in the long-term (Niemeyer and Vale, 2022). In addition, there is a high global financial gap for adaptation measures that exceed current available cash flows (Brandon et al., 2025). Adaptation actions are often misinterpreted as avoiding climate-related losses only, when it delivers economic, social, and environmental returns (Brandon et al., 2025).